Halo Infinite

One website I recently discovered thanks to GTA and their collectibles is mapgenie. You can navigate to this website for reference as you knock each tower out:

https://mapgenie.io/halo-infinite

You'll most likely discover these towers throughout the campaign, and they are fairly easy to take out. Each one looks exactly the same and some will even show up on your map as you unlock more audio logs. If you have access to a wasp, then it'll make the process 10x easier to fly to each one, blow it up, and move onto the next. The achievement should pop after the last one has been destroyed.

There are 40 towers altogether. You'll know if you walk by one if you hear a grunt talking as if you were listening to talk show radio.

There are 40 in total and you will not see them on the map like other collectibles, but they are one of the easiest if you have a map or some guide showing the locations.

Fastest way to complete is to ignore them almost completely until you get a wasp flying mount and then it'l be done in 1h max

Here is locations if you need them:

One thing to note, if you're like me and tried to do this just off map icons, not all of them will show up on the map by capturing bases. It seems they will show up if you see them or get close enough to the towers, but you will likely be missing more than a few unless you covered every inch of the map. You can generally hear a grunt talking if you're close enough, and even see subtitles for what he's saying. I used Halo Canon's guide for the ones I could not find on my own, since it has the map view and the surrounding view shown. You can keep track of how many you have in each area by scrolling over the area and checking the right most icon for the Propaganda Tower tracker.

There are 40 propaganda towers to destroy in the game's campaign.
They only appear on the map if you are very close.

Here is a video to help you find them all: